1. Field of the Invention
This invention relates to a stroller, and more particularly to a foldable stroller, which includes a handle unit that can be folded on a wheel unit and that can be positioned firmly relative to the remaining parts of the stroller when unfolded from the wheel unit.
2. Description of the Related Art
Referring to FIG. 1, a conventional foldable stroller 1 is shown to include a front wheel unit 11, a handle unit 12, a rear wheel unit 13, a pair of left and right pivot members 14 that are disposed fixedly on the front wheel unit 11, two connectors 15, a pair of left and right retaining members 16, and a pair of left and right control mechanisms 17. The front wheel unit 11 includes a pair of inclined left and right lower rods 111. The handle unit 12 includes a pair of inclined left and right upper rods 121, which are connected respectively and rotatably to the pivot elements 14 by means of two pivot pins 122. The connectors 15 are disposed respectively and fixedly on the upper rods 121, and are connected pivotally to the rear wheel unit 13. The retaining members 16 are biased forwardly and downwardly to press against the lower rods 111, respectively, thereby engaging retaining holes 161 in the retaining members 16 with the upper ends of the lower rods 111 accordingly.
When it is desired to fold the stroller 1, the control mechanisms 17 are actuated so as to move the retaining members 16 rearwardly and upwardly away from the lower rods 111. As soon as the holes 161 in the retaining members 16 separate from the upper ends of the lower rods 111, the handle unit 12 is rotated clockwise about the pivot pins 122 so that the handle unit 12 and the rear wheel unit 13 can be folded on the front wheel unit 11. Thereafter, when it is desired to unfold the stroller 1, the handle unit 12 is rotated counterclockwise to a position where the holes 161 in the retaining members 16 are aligned with the lower rods 111 such that the retaining members 16 are biased to engage the holes 161 with the upper ends of the lower rods 111, thereby locking the upper rods 121 relative to the lower rods 111.
The aforesaid conventional foldable stroller 1 suffers from a drawback in that the holes 161 in the retaining members 16 are sized so that when the upper ends of the lower rods 111 engage the holes 161, significant clearances are present between the upper ends of the lower rods 111 and the walls of the retaining members 16 defining the holes 161 in order to ensure smooth engagement between the lower rods 111 and the holes 161. As such, when the stroller 1 is unfolded, the handle unit 12 cannot be positioned firmly relative to the front and rear wheel units 11, 13.
The object of this invention is to provide a foldable stroller, which includes a handle unit that can be positioned firmly relative to the remaining parts of the stroller when the stroller is unfolded.
According to this invention, a foldable stroller includes a front wheel unit with a pair of rearwardly and upwardly inclined left and right lower rods, each of which has an upper end. Two positioning members are disposed respectively and fixedly on the upper ends of the left and right lower rods. Each of the positioning members has an upper end, which is formed with:
a rearwardly and upwardly inclined planar positioning surface forming an acute angle with respect to the longitudinal direction of the left and right lower rods, and
a guiding surface extending generally and downwardly from the upper end of the positioning surface.
A handle unit includes a grip and a pair of inclined left and right upper rods that are fixed to and that extend respectively, forwardly and downwardly from two opposite ends of the grip. Each of the left and right upper rods is parallel to the left and right lower rods, and has a lower end. Two guideway members are disposed respectively and fixedly on the lower ends of the left and right upper rods, and are connected respectively and pivotally to the positioning members. A rear wheel unit is disposed pivotally on the lower ends of the left and right upper rods, and is located behind the front wheel unit. A link interconnects pivotally the front and rear wheel units. Each of a pair of left and right control mechanisms includes:
a sliding element disposed slidably within a respective one of the guideway members and guided to move in the longitudinal direction of the left and right lower rods, the sliding element being formed with a planar abutment surface that engages the positioning surface of a respective one of the positioning members and that has a lower end, and an engaging surface that extends generally and upwardly from the lower end of the abutment surface, the abutment surface and the engaging surface defining a tip of the sliding element therebetween;
a resilient element for biasing the abutment surface of the sliding element to engage the positioning surface of the respective one of the positioning members, thereby preventing rotation of the left and right upper rods relative to the left and right lower rods;
an actuator element disposed operably on the handle unit; and
an elongated connecting element having an upper end that is fastened to the actuator element, and a lower end that is fastened to the sliding element so that actuation of the actuator element results in separation of the abutment surface of the sliding element from the positioning surface of the positioning member against the biasing action of the resilient element, thereby permitting folding of both the handle unit and the rear wheel unit on the front wheel unit, after which the handle unit and the rear wheel unit can be unfolded from the front wheel unit so that the engaging surface of the sliding element slides over the guiding surface of the respective one of the positioning members such that the abutment surface of the sliding element is biased by the resilient element to engage the positioning surface of the respective one of the positioning members.